SPI Biology · Formula sheet
Ecology and Environment formulas
1 formula, 4 reference tables and 7 common traps for SPI Biology Ecology and Environment, grouped by subtopic.
Ecosystems and Food Chains
Learn this subtopic in the notesThe ten percent law of energy flow
Energy at the next level
The parts of an ecosystem
| Component | Living or not | Examples |
|---|---|---|
| Producers | Living | Grass, trees, algae |
| Consumers | Living | Deer, frog, lion |
| Decomposers | Living | Bacteria, fungi |
| Abiotic factors | Non-living | Air, water, soil, sunlight An ecosystem includes the non-living part too, not living things alone. |
Food chains, trophic levels and pyramids
| Trophic level | Name | Example (grassland) | Example (pond) |
|---|---|---|---|
| First | Producer | Grass | Phytoplankton |
| Second | Herbivore (primary consumer) | Grasshopper | Small crustaceans |
| Third | Carnivore (secondary consumer) | Frog | Small fish |
| Fourth | Top carnivore | Snake | Large fish Decomposers are not a level in the chain. |
The pyramid of energy is always upright; a pond's pyramid of biomass can have a narrow base.
Common traps
An ecosystem as living things only
A community is the living things alone. An ecosystem adds the non-living part (air, water, soil, light) that they live in and use.
Putting decomposers in the chain
Producers, consumers and decomposers are the parts of an ecosystem. A food chain is producers, herbivores and carnivores; decomposers work on every level from the side.
Every pyramid is upright
The pyramid of energy is always upright, but a pond's pyramid of biomass can be narrow at the bottom, because tiny producers are eaten as fast as they grow.
Mixing up the 1% and the 10%
Plants store about 1% of sunlight; about 10% of energy passes from one animal level to the next. A question about sunlight wants 1%.
Waste and Wildlife Conservation
Learn this subtopic in the notesBiodegradable and non-biodegradable waste
| Waste | Kind | Why |
|---|---|---|
| Fruit and vegetable peels | Biodegradable | Microbes break them down |
| Paper | Biodegradable | Microbes break it down |
| Plastic plates and bags | Non-biodegradable | No microbe can break them down Plastic is avoided because it is non-biodegradable, not because it is light or toxic. |
| Glass bottles | Non-biodegradable | No microbe can break them down |
Threatened species and migratory birds
| Category | What it means | Example |
|---|---|---|
| Extinct | Found nowhere any more | Dodo |
| Endangered | On the verge of extinction | Bengal tiger |
| Vulnerable | Falling, likely to become endangered | One-horned rhinoceros |
| Rare | Numbers much declined, endemic, may vanish fast | Red panda, musk deer Endemic plus a sharp decline: that is the book's definition of rare. |
Indeterminate has no fixed example: it is for species too little known to place.
Common traps
Taking a good habit for the harmful one
Segregating waste, reusing utensils and cutting down CFCs protect the environment. A question asking what harms it wants the bad habit, such as using piles of disposable plates.
Endangered for every shrinking species
Endangered means on the very edge of extinction. A species whose numbers have dropped sharply and which lives in one region only is called rare in the Class 10 book.
Thinking winter migrants arrive in the middle of winter
Siberian cranes arrive at the start of winter, in December, and stay till about March. January and February fall in the middle of their stay.